Spectral Linewidth Adjusting Method and Electronic Device Manufacturing Method

The present application claims the benefit of Japanese Patent Application No. JP2024-160149, filed on Sep. 17, 2024, the entire contents of which are hereby incorporated by reference.

The present disclosure relates to a spectral linewidth adjusting method and an electronic device manufacturing method.

Recently, in a semiconductor exposure apparatus, improvement in resolution has been desired for miniaturization and high integration of semiconductor integrated circuits. For this purpose, an exposure light source that outputs light having a shorter wavelength has been developed. For example, as a gas laser apparatus for exposure, a KrF excimer laser apparatus that outputs a laser beam having a wavelength of about 248 nm and an ArF excimer laser apparatus that outputs a laser beam having a wavelength of about 193 nm are used.

Spectral linewidths of spontaneous oscillation beams of the KrF excimer laser apparatus and the ArF excimer laser apparatus are as wide as from 350 pm to 400 pm. Therefore, when a projection lens is formed of a material that transmits ultraviolet light such as KrF and ArF laser beams, chromatic aberration may occur. As a result, the resolution may decrease. Thus, the spectral linewidth of the laser beam output from the gas laser apparatus needs to be narrowed to an extent that the chromatic aberration is ignorable. Therefore, in a laser resonator of the gas laser apparatus, a line narrowing module (LNM) including a line narrowing element (such as etalon or grating) may be provided in order to narrow the spectral linewidth. Hereinafter, a gas laser apparatus with a narrowed spectral linewidth is referred to as a line narrowing gas laser apparatus.

Patent Document 1: International Publication No. WO2024/057673

Patent Document 2: Japanese Unexamined Patent Application Publication No. 2010-238684

A spectral linewidth adjusting method according to one aspect of the present disclosure is for a pulse laser beam output by a laser apparatus. The laser apparatus includes a first semiconductor laser configured to output first continuous light, a first amplifier configured to amplify a portion of the first continuous light in synchronization with a light emission trigger signal received from an external device and to convert the portion of the first continuous light to a first pulse laser beam, a second amplifier configured to amplify a portion of the first pulse laser beam using a first trigger signal generated in synchronization with the light emission trigger signal and to convert the portion of the first pulse laser beam to a second pulse laser beam, a second semiconductor laser configured to output second continuous light, a third amplifier configured to amplify a portion of the second continuous light using a second trigger signal generated in synchronization with the light emission trigger signal and to convert the portion of the second continuous light to a third pulse laser beam, an optical phase modulator disposed in an optical path of the second continuous light between the second semiconductor laser and the third amplifier, a modulation signal generator configured to output a modulation signal to be supplied to the optical phase modulator, and a wavelength conversion system configured to perform sum-frequency mixing of the second pulse laser beam and the third pulse laser beam for wavelength conversion and to output a fourth pulse laser beam. The spectral linewidth adjusting method includes a first step and a second step. In the first step, at least one of a timing of the first trigger signal and a timing of the second trigger signal is adjusted and a spectrum of the fourth pulse laser beam is adjusted to a first spectrum in a non-Gaussian shape. In the second step, a wavelength of the second continuous light is modulated within time corresponding to one pulse of the third pulse laser beam and the spectrum of the fourth pulse laser beam is adjusted to a second spectrum having a spectral linewidth wider than the first spectrum by causing the modulation signal generator to generate the modulation signal of a same pattern synchronized with the light emission trigger signal and supplying the modulation signal of the same pattern to the optical phase modulator.

An electronic device manufacturing method according to another aspect of the present disclosure includes generating a fourth pulse laser beam by a laser apparatus, outputting the fourth pulse laser beam to an exposure apparatus, and exposing a photosensitive substrate to the fourth pulse laser beam within the exposure apparatus to manufacture an electronic device. The laser apparatus includes a first semiconductor laser configured to output first continuous light, a first amplifier configured to amplify a portion of the first continuous light in synchronization with a light emission trigger signal received from an external device and to convert the portion of the first continuous light to a first pulse laser beam, a second amplifier configured to amplify a portion of the first pulse laser beam using a first trigger signal generated in synchronization with the light emission trigger signal and to convert the portion of the first pulse laser beam to a second pulse laser beam, a second semiconductor laser configured to output second continuous light, a third amplifier configured to amplify a portion of the second continuous light using a second trigger signal generated in synchronization with the light emission trigger signal and to convert the portion of the second continuous light to a third pulse laser beam, an optical phase modulator disposed in an optical path of the second continuous light between the second semiconductor laser and the third amplifier, a modulation signal generator configured to output a modulation signal to be supplied to the optical phase modulator, and a wavelength conversion system configured to perform sum-frequency mixing of the second pulse laser beam and the third pulse laser beam for wavelength conversion and to output the fourth pulse laser beam. The laser apparatus adjusts at least one of a timing of the first trigger signal and a timing of the second trigger signal, and adjusts a spectrum of the fourth pulse laser beam to a first spectrum in a non-Gaussian shape. The laser apparatus modulates a wavelength of the second continuous light within time corresponding to one pulse of the third pulse laser beam and adjusts the spectrum of the fourth pulse laser beam to a second spectrum having a spectral linewidth wider than the first spectrum by causing the modulation signal generator to generate the modulation signal of a same pattern synchronized with the light emission trigger signal and supplying the modulation signal of the same pattern to the optical phase modulator.

1.1.1 Configuration 1.1.2 Operation 1.1 Laser Apparatus 1.2 Configuration of Pseudorandom Signal Generator 1.3 Example 1 of Pseudorandom Signal Generator Operation 1.4 Effect and Advantage 1.5 Example 2 of Pseudorandom Signal Generator Operation 1.6 Effect and Advantage 1.7 Problem 1. Comparative Example 2.1.1 Laser Apparatus 2.1.2 Solid-State Seeder 2.1 Configuration 2.2.1 Time of Laser Operation Execution 2.2.2 Time of Adjustment 2.2.2.1 First Step 2.2.2.2 Second Step 2.2 Operation 2.3 Effect and Advantage 2. Embodiment 1 3.1 Configuration 3.2 Operation 3.3 Effect and Advantage 3. Embodiment 2 4 4.1 Configuration 4.2 Operation 4.3 Effect and Advantage . Embodiment 3 5. Electronic Device Manufacturing Method 6. Others

Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. The embodiments described below show some examples of the present disclosure and do not limit contents of the present disclosure. In addition, all configurations and operations described in the embodiments are not necessarily essential as configurations and operations of the present disclosure. Here, the same components are denoted by the same reference signs, and any redundant description thereof is omitted.

1 FIG. 10 schematically illustrates a configuration of a laser apparatusaccording to a comparative example. The comparative example of the present disclosure is an example recognized by the applicant as known only by the applicant, and is not a publicly known example admitted by the applicant.

10 20 30 20 40 46 50 The laser apparatusincludes a solid-state seederas a master oscillator (MO) that generates a pulse laser beam, an excimer amplifieras a power amplifier (PA) that amplifies output light of the solid-state seeder, a monitor module, an exit shutter, and a laser control processor.

20 The solid-state seederoutputs a pulse laser beam having a central wavelength of about 193.4 nm.

30 31 32 33 34 35 31 36 36 37 37 38 31 a b a b The excimer amplifierincludes a chamber, a pulse power module (PPM), a charger, a convex mirror, and a concave mirror. The chamberincludes windowsand, a pair of electrodesand, and an electric insulating member. Inside the chamber, an ArF laser gas is supplied from an unillustrated gas supply device. The ArF laser gas includes an Ar gas, an F2 gas, and an Ne gas.

32 39 33 32 33 33 32 50 The PPMincludes a switchand an unillustrated charging capacitor. The chargerholds electric energy to be supplied to the PPM. The chargeris connected to the unillustrated charging capacitor. The chargercharges the charging capacitor of the PPMin accordance with a command from the laser control processor.

32 37 31 38 37 b a The PPMis connected with the electrodein the chambervia a feedthrough in the electric insulating member. The electrodeis connected to a ground potential.

36 36 37 37 a b a b The windowsandare disposed such that a pulse laser beam amplified by discharge excitation between the electrodesandpasses through.

34 35 20 37 37 a b The convex mirrorand the concave mirrorare disposed such that the pulse laser beam output from the solid-state seederpasses through a discharge space between the electrodesandthree times so as to expand the beam.

40 41 42 43 44 41 30 41 42 41 40 The monitor moduleincludes beam splittersand, a spectrum monitor, and a photosensor. The beam splitteris disposed such that, on an optical path of the pulse laser beam output from the excimer amplifier, the pulse laser beam reflected by the beam splitterenters the beam splitter. The beam splittermay be disposed outside the monitor module.

42 42 43 42 44 The beam splitteris disposed such that the pulse laser beam reflected by the beam splitterenters the spectrum monitorand the pulse laser beam transmitted through the beam splitterenters the photosensor.

43 43 The spectrum monitormonitors a spectrum of the incident pulse laser beam, and detects an oscillation wavelength of the incident pulse laser beam. The spectrum monitormay be, for example, an etalon spectrometer. The etalon spectrometer includes a diffusion plate that diffuses sample light, an etalon, a light condensing lens disposed on an exit side of the etalon, and a photodiode array disposed on a focal plane of the light condensing lens for detecting a pattern of interference fringes, and can detect the wavelength by measuring a diameter of the interference fringes.

44 44 The photosensordetects pulse energy of the incident pulse laser beam. The photosensormay be, for example, a photodiode.

46 10 41 10 46 The exit shutteris disposed on an optical path of the pulse laser beam output from the laser apparatusto the outside, and is configured so as to switch between output of the pulse laser beam to the outside and light shielding. The pulse laser beam transmitted through the beam splitteris output from the laser apparatusvia the exit shutter.

10 60 10 60 10 60 The laser apparatusis connected with an exposure apparatusvia an unillustrated beam delivery unit (BDU). The BDU is an optical system that transmits the pulse laser beam from the laser apparatusto the exposure apparatus. The pulse laser beam output from the laser apparatusenters the exposure apparatusvia the BDU.

60 61 61 60 61 50 60 The exposure apparatusincludes an exposure control processor. The exposure control processorcontrols the exposure apparatus. In addition, the exposure control processoris connected with the laser control processor. The exposure apparatusis an example of an “external device” in the present disclosure.

50 61 50 30 20 10 The laser control processorreceives a target center wavelength, a target linewidth, target pulse energy, and a light emission trigger signal from the exposure control processor. The laser control processorsends a trigger A signal and a charging voltage value to the excimer amplifierand a trigger B signal, a linewidth control signal, a temperature value, and a current value to the solid-state seederto operate the laser apparatus, and controls the pulse laser beam. In the present specification, a processor is a processing device including a storage device in which a control program is stored, and a CPU (Central Processing Unit) which executes the control program. The processor is specifically configured or programmed to execute various kinds of processing included in the present disclosure.

2 FIG. 20 20 100 110 130 140 150 160 schematically illustrates a configuration of the solid-state seeder. The solid-state seederincludes a first solid-state laser device, a second solid-state laser device, a dichroic mirror, a wavelength conversion system, a pseudorandom signal generator, and a solid-state seeder control processor.

20 100 110 140 The solid-state seederhas a system configuration in which a pulse laser beam having a wavelength of about 1554 nm output from the first solid-state laser deviceand a pulse laser beam having a wavelength of about 257.6 nm output from the second solid-state laser deviceare converted to a pulse laser beam having a wavelength of about 193.4 nm through two-stage sum-frequency mixing in the wavelength conversion system.

100 101 102 101 The first solid-state laser deviceincludes a semiconductor laser systemand a solid-state amplifier. The semiconductor laser systemincludes a first semiconductor laser configured to CW (Continuous Wave) oscillate in a single longitudinal mode at the wavelength of about 1554 nm, and to output first continuous light.

102 The solid-state amplifiermay be an optical parametric amplifier (OPA). The OPA is, for example, PPLN (periodically poled lithium niobate: periodically poled lithium niobate crystal) or PPKTP (periodically poled KTP: periodically poled titanyl potassium phosphate crystal).

102 101 The solid-state amplifieris configured to pulse-amplify seed light by receiving input of a pulse laser beam having a wavelength of 1030 nm to be described later as pump light and a laser beam output from the semiconductor laser systemas the seed light.

110 111 112 113 114 115 116 The second solid-state laser deviceincludes a semiconductor laser system, an optical phase modulator, a solid-state amplifier, an LBO crystaland a CLBO crystalwhich are two nonlinear crystals that perform second harmonic generation twice and perform wavelength conversion so that an optical frequency is quadrupled, and a dichroic mirror. The “LBO” is represented by a chemical formula LiB3O5. The “CLBO” is represented by a chemical formula CsLiB6O10.

111 The semiconductor laser systemincludes a second semiconductor laser configured to CW oscillate in the single longitudinal mode at the wavelength of about 1030 nm, and to output second continuous light.

113 113 102 The solid-state amplifiermay include, for example, a Yb fiber amplifier and a Yb:YAG crystal. The solid-state amplifiermay be configured same as the solid-state amplifier.

112 111 113 The optical phase modulatoris disposed on an optical path between the semiconductor laser systemand the solid-state amplifier.

116 114 115 116 102 113 114 116 113 114 102 The dichroic mirroris disposed on an optical path between the LBO crystaland the CLBO crystal, highly transmits the pulse laser beam having the wavelength of about 515 nm, and highly reflects the pulse laser beam having the wavelength of about 1030 nm. The dichroic mirroris disposed such that the highly reflected pulse laser beam having the wavelength of about 1030 nm enters the solid-state amplifieras the pump light. An unillustrated beam splitter may be disposed between the solid-state amplifierand the LBO crystalinstead of the dichroic mirrorso that the pulse laser beam output from the solid-state amplifieris branched to enter the LBO crystaland the solid-state amplifier.

130 100 110 140 The dichroic mirroris configured to highly reflect the pulse laser beam having the wavelength of about 1554 nm output from the first solid-state laser deviceand to highly transmit the pulse laser beam having the wavelength of about 257.6 nm output from the second solid-state laser device, and is disposed such that both pulse laser beams coaxially enter the wavelength conversion system.

140 141 142 143 144 141 142 143 144 The wavelength conversion systemincludes a CLBO crystal, a CLBO crystal, a rotation stage, and a rotation stage. The CLBO crystaland the CLBO crystalare disposed on the rotation stageand the rotation stage, each including a piezoelectric element, so that an incident angle of each crystal can be changed at a high speed.

150 112 150 2 FIG. The pseudorandom signal generatoroutputs a modulation signal to be supplied to the optical phase modulator. The pseudorandom signal generatoris formed of a multi-stage shift register and a variable bandpass filter (digital filter) both of which are not illustrated in.

160 20 160 100 110 130 140 150 50 The solid-state seeder control processorcontrols a wavelength, power, a pulse waveform, a spectrum, and the like of the laser beam output by the solid-state seeder. The solid-state seeder control processorcontrols the first solid-state laser device, the second solid-state laser device, the dichroic mirror, the wavelength conversion system, and the pseudorandom signal generatorbased on input from the laser control processor.

20 110 100 140 In the solid-state seeder, by fixing the wavelength of the pulse laser beam output from the second solid-state laser deviceand changing the wavelength of the pulse laser beam output from the first solid-state laser devicefor each pulse, the wavelength of the pulse laser beam output from the wavelength conversion systemcan be changed.

110 160 110 160 111 The operation of the second solid-state laser deviceis as follows. The solid-state seeder control processorfixes an oscillation wavelength of the second solid-state laser deviceat 1030 nm. That is, the solid-state seeder control processorfixes a current value of the second semiconductor laser in the semiconductor laser system, causes the second semiconductor laser to continuously oscillate, and causes a CW laser beam to be output from the second semiconductor laser.

111 112 113 The CW laser beam output from the semiconductor laser systemis phase-modulated by the optical phase modulatorand enters the solid-state amplifier.

160 50 150 150 The solid-state seeder control processortransmits a timing signal same as the trigger B signal acquired from the laser control processorand a reset signal to the shift register of the pseudorandom signal generatorto the pseudorandom signal generator.

150 160 The pseudorandom signal generatorreceives the reset signal from the solid-state seeder control processorto the shift register and generates a pseudorandom signal of a same pattern in synchronization with the trigger B signal.

From the pseudorandom signal, unneeded spectral components of high frequency components are eliminated by the variable bandpass filter.

112 150 The optical phase modulatorphase-modulates the CW laser beam with the pseudorandom signal limited to an appropriate frequency band from the pseudorandom signal generatorto change the spectrum.

150 150 112 When a cutoff frequency of the variable bandpass filter of the pseudorandom signal generatoris changed to a high frequency side, a spectral linewidth of the light becomes wide, and when it is changed to a low frequency side, the spectral linewidth becomes narrow. In addition, the waveform and the spectrum of the pseudorandom signal are changed by changing a timing of inputting the reset signal to the shift register of the pseudorandom signal generatoras well, and the spectral linewidth of the laser beam output from the optical phase modulatoris also changed.

When the spectral linewidth is to be controlled, the spectral linewidth of the laser beam is measured, and a frequency of the pseudorandom signal is adjusted based on the measured spectral linewidth. Specifically, the cutoff frequency of the variable bandpass filter is adjusted.

160 112 113 113 The solid-state seeder control processorpulse-amplifies the CW laser beam phase-modulated by the optical phase modulatorby the solid-state amplifierin synchronization with the trigger B signal. The solid-state amplifieroutputs the pulse laser beam having the wavelength of 1030 nm.

113 114 116 115 114 115 The pulse laser beam having the wavelength of 1030 nm output from the solid-state amplifieris converted to second harmonic light having the wavelength of 515 nm in the LBO crystal. The second harmonic light having the wavelength of 515 nm is highly transmitted through the dichroic mirrorand is converted to the pulse laser beam having the wavelength of 257.6 nm by the CLBO crystal. The LBO crystaland the CLBO crystalare examples of a “wavelength conversion crystal” in the present disclosure.

116 114 102 100 Here, the dichroic mirrorhighly reflects the pulse laser beam having the wavelength of 1030 nm, which has not been wavelength-converted in the LBO crystal, to make it enter the solid-state amplifierof the first solid-state laser deviceas the pump light.

50 160 100 101 100 160 101 On the other hand, the laser control processorand the solid-state seeder control processorcan change the wavelength of the pulse laser beam output from the first solid-state laser devicearound 1554 nm by controlling a temperature value and/or a current value of the first semiconductor laser in the semiconductor laser systemof the first solid-state laser device. The solid-state seeder control processormay change the oscillation wavelength of the semiconductor laser systemfor each pulse.

100 110 141 140 142 140 The pulse laser beam having the wavelength of about 1554 nm output from the first solid-state laser deviceand the pulse laser beam having the wavelength of 257.6 nm output from the second solid-state laser deviceare subjected to sum-frequency mixing by the CLBO crystalof the wavelength conversion system, and wavelength-converted to the pulse laser beam having the wavelength of about 220.9 nm. Furthermore, by the CLBO crystal, the pulse laser beam having the wavelength of about 220.9 nm and the pulse laser beam having the wavelength of about 1554 nm are subjected to sum-frequency mixing, and is wavelength-converted to the pulse laser beam having the wavelength of about 193.4 nm. Then, the pulse laser beam having the wavelength of about 193.4 nm is output from the wavelength conversion system.

20 30 A variable range of the wavelength of the pulse laser beam output from the solid-state seederis from about 193.2 nm to 193.5 nm as an amplification wavelength band of the excimer amplifier.

20 31 30 39 32 20 30 As discharge occurs in synchronization with entry of the pulse laser beam output from the solid-state seederto the discharge space of the chamberof the excimer amplifier, the trigger A signal is input to the switchof the PPM. As a result, the pulse laser beam output from the solid-state seederis amplified by the excimer amplifierthrough three-time passing.

30 41 42 40 43 44 The pulse laser beam amplified by the excimer amplifieris sampled by the beam splitterand the beam splitterof the monitor module, and the spectrum and the pulse energy are measured by the spectrum monitorand the photosensor.

30 50 160 160 101 50 101 101 160 From the measured spectrum of the pulse laser beam output from the excimer amplifier, the laser control processorsends a center wavelength control signal to the solid-state seeder control processorso that a center wavelength approaches the target center wavelength which is a target value. The solid-state seeder control processorsends a command value of the temperature value and the current value to the semiconductor laser systembased on the control signal acquired from the laser control processor. The semiconductor laser systemchanges a temperature or a current of the semiconductor laser of the semiconductor laser systemto change the oscillation wavelength based on the command value of the temperature value and the current value acquired from the solid-state seeder control processor.

30 50 160 160 150 50 Further, from the measured spectrum of the pulse laser beam output from the excimer amplifier, the laser control processorsends a spectral linewidth control signal to the solid-state seeder control processorso that the spectral linewidth approaches the target linewidth which is the target value. The solid-state seeder control processorchanges a signal bandwidth and power of the modulation signal output from the pseudorandom signal generatorbased on the control signal acquired from the laser control processor.

112 112 150 The optical phase modulatorchanges the spectral linewidth of the laser beam output from the optical phase modulatorby the signal bandwidth and the power of output from the pseudorandom signal generator.

50 33 30 Further, the laser control processorchanges a charging voltage of the chargerso that the measured pulse energy of the pulse laser beam output from the excimer amplifierapproaches the target pulse energy which is the target value.

112 112 By the configuration and the operation, the wavelength of the second continuous light is modulated within time corresponding to one pulse of the pulse laser beam, and the spectral linewidth of the pulse laser beam is adjusted. The pseudorandom signal of the same pattern is generated in synchronization with the trigger B signal synchronized with the timing of generation of the pulse laser beam, and is superimposed onto the optical phase modulator. Therefore, the modulation signal of the same waveform for each pulse is superimposed onto the optical phase modulator, and the spectrum of the superimposed signal is also the same for each pulse.

112 Thus, since the pulse laser beam output from the optical phase modulatoris modulated the same for each pulse, the spectrum becomes the same for each pulse, and the spectral linewidth also becomes the same for each pulse and becomes stable.

150 Note that when the spectrum is changed by operating the pseudorandom signal generatorin synchronization with the trigger B signal, in order to make its shape unimodal, a flow of a search to update an initial value of the shift register until the spectrum becomes unimodal is required.

An initial value setting circuit is added to the pseudorandom signal generator, and the initial value of the shift register is adjusted so that the generated spectrum becomes unimodal.

3 FIG. 150 150 151 152 153 154 155 156 illustrates an example of the pseudorandom signal generator. The pseudorandom signal generatorincludes a shift register, at least one exclusive OR (XOR) circuit, a variable bandpass filter, an amplifier, a trigger regeneration circuit, and an initial value setting circuit.

151 1 36 11 36 152 152 1 36 36 153 153 154 153 154 160 36 36 The shift registeris configured such that 36 D flip-flops FFto FFare connected in series, Q output of the D flip-flop FFof an 11th stage and Q output of the D flip-flop FFof a 36th stage are input to the XOR circuit, and output of the XOR circuitis fed back to the D flip-flop FFof a 1st stage. The Q output of the D flip-flop FFof the 36th stage repeats a same random pattern (pseudorandom pattern) every time a clock is counted 2−1 times (period 2−1). The Q output of the D flip-flop FFof the 36th stage is input to the variable bandpass filter, and the output of the variable bandpass filteris amplified and output by the amplifier. A passband of the variable bandpass filterand output power of the amplifierare controlled by control signals from the solid-state seeder control processor.

155 1 36 160 150 The trigger regeneration circuitgenerates a timing signal that changes an initial value of the D flip-flops FFto FFfrom the trigger B signal from the solid-state seeder control processorand a high-speed internal clock of the pseudorandom signal generator.

156 1 36 1 36 160 155 In the initial value setting circuit, a signal is sent to a SET terminal or a CLR terminal of each of the D flip-flops FFto FFso that the initial value of each of the D flip-flops FFto FFis “0” or “1” (“Low” or “Hi”) by the control signal from the solid-state seeder control processorin synchronization with the timing signal generated by the trigger regeneration circuit. For example, when the initial value is to be set to “0”, the signal is sent to the CLR terminal, and when the initial value is to be set to “1”, the signal is sent to the SET terminal.

152 151 154 154 While an example using D flip-flops in 36 stages has been described here, the number of stages of the D flip-flops is not limited to this example, and the number of stages, a feedback position, and the number of XOR circuitsmay be appropriately arranged and connected according to a well-known feedback polynomial, for example. Further, the shift registerformed of the D flip-flops in multiple stages may be formed of an FPGA (Field Programmable Gate Array) or the like. In addition, while the power of the modulation signal to be output is adjusted in the amplifierhere, output power may be adjusted by inserting a variable attenuator in a succeeding stage or a preceding stage of the amplifier.

152 150 An XNOR circuit may be used instead of the XOR circuit. The pseudorandom signal generatoris an example of a “modulation signal generator” in the present disclosure.

4 FIG. 1 50 30 43 40 illustrates a flowchart of a control example of the spectral linewidth in the comparative example. In step S, the laser control processormeasures a spectrum of an output pulse laser beam of the excimer amplifierusing the spectrum monitorof the monitor module.

2 50 2 50 3 In step S, the laser control processorexamines whether the measured spectrum is unimodal or multimodal and determines whether the spectrum has a unimodal shape. If a determination result in step Sis NO determination, that is, if the spectrum is multimodal, the laser control processorproceeds to step S.

3 50 151 160 1 In step S, the laser control processorchanges the initial value of the shift registervia the solid-state seeder control processorand returns to step S.

2 50 4 On the other hand, if the determination result in step Sis YES determination, that is, if the spectrum is unimodal, the laser control processorproceeds to step S.

4 50 In step S, the laser control processormeasures the spectral linewidth from the acquired spectrum.

5 50 61 4 In step S, the laser control processorcalculates a difference between the target linewidth, which is periodically updated by the exposure control processor, and a measurement result in step S.

6 50 6 50 1 In step S, the laser control processordetermines whether the calculated difference is within an allowable range. If a determination result in step Sis YES determination, that is, if the difference is within the allowable range, the laser control processorreturns to step S.

6 50 7 On the other hand, if the determination result in step Sis NO determination, that is, if the difference is not within the allowable range, the laser control processorproceeds to step S.

7 50 5 112 1 153 In step S, the laser control processordetermines the power of the modulation signal by a function indicating a relationship between a square root of the power of the modulation signal and the spectral linewidth obtained in advance and the difference calculated in step S, changes the power of the modulation signal to be superimposed onto the optical phase modulator, and returns to step S. However, instead of the relationship between the square root of the power of the modulation signal and the spectral linewidth obtained in advance, a table list of the relationship between the square root of the power of the modulation signal and the spectral linewidth that has been recorded may be used. Alternatively, instead of adjusting the power of the modulation signal, the bandwidth of the modulation signal may be adjusted using the variable bandpass filter.

151 Adjusting the initial value of the shift registerallows control to be the target spectral linewidth with the unimodal spectrum at all times.

Since the relationship between the square root of the power of the modulation signal and the spectral linewidth has high linearity, linewidth control can be executed more easily and accurately by adjusting the power of the modulation signal.

Further, since the relationship between the bandwidth of the modulation signal and the spectral linewidth has high linearity, the linewidth control can be executed more easily and accurately by adjusting the bandwidth of the modulation signal.

5 FIG. 4 FIG. 1 5 illustrates a flowchart of another control example of the spectral linewidth in the comparative example. In this example, the spectral linewidth is coarsely adjusted by the bandwidth of the modulation signal and finely adjusted by the power of the modulation signal. Processing of steps Sto Sis the same as that in the flowchart illustrated in.

8 5 50 5 8 50 9 In step Sfollowing step S, the laser control processordetermines whether the difference calculated in step Sis within the allowable range of coarse adjustment. If a determination result in step Sis NO determination, that is, if the difference is not within the allowable range of the coarse adjustment, the laser control processorproceeds to step S.

9 50 112 153 9 160 50 9 50 1 In step S, the laser control processorchanges the bandwidth of the modulation signal to be superimposed onto the optical phase modulatorby the variable bandpass filter. The operation in step Smay be performed by the solid-state seeder control processorin accordance with a command of the laser control processor. After step S, the laser control processorreturns to step S.

8 50 10 10 50 5 10 50 1 If the determination result in step Sis YES determination, that is, if the difference is within the allowable range of the coarse adjustment, the laser control processorproceeds to step S. In step S, the laser control processordetermines whether the difference calculated in step Sis within the allowable range of fine adjustment. If a determination result in step Sis YES determination, that is, if the difference is within the allowable range of the fine adjustment, the laser control processorreturns to step S.

10 50 7 7 7 50 1 7 160 50 4 FIG. If the determination result in step Sis NO determination, that is, if the difference is not within the allowable range of the fine adjustment, the laser control processorproceeds to step S. The processing of step Sis the same as that in the flowchart illustrated in. After step S, the laser control processorreturns to step S. The operation in step Smay be performed by the solid-state seeder control processorin accordance with a command of the laser control processor.

151 150 112 Adjusting the initial value of the shift registerallows the control to be the target spectral linewidth with the unimodal spectrum at all times. Further, since a method of changing the bandwidth of the modulation signal when the spectral linewidth is coarsely adjusted and changing the power of the modulation signal when the spectral linewidth is finely adjusted is adopted, an amount of changing the power of the modulation signal is small as compared with a case where the linewidth is controlled only by the power of the modulation signal. Thus, stability of the entire modulation signal generator including the pseudorandom signal generatoris improved, a thermal load or the like applied to the optical phase modulatoris reduced, and stable control is made possible.

Further, as compared with a case where the linewidth is controlled only by the bandwidth of the modulation signal, when the change of the power of the modulation signal is used, a set resolution can be made finer.

150 151 153 112 In technology of adjusting the spectrum of the laser beam by the pseudorandom signal generatorformed of the multi-stage shift registerand the variable bandpass filterand the optical phase modulator, when the spectral linewidth defined by a full width at half maximum (FWHM), an E95 width, or the like is to be widened while maintaining unimodality of a Gaussian waveform or the like, since magnitude of an amplitude of optical phase modulation is finite, an adjustment range of the spectral linewidth (an upper limit of the spectral linewidth in particular) is limited.

0 5 For example, when the spectral linewidth on a wide side such as 0.5 pm with respect to the E95 linewidth of 0.2 pm or more and.pm or less or the like, which is demanded for semiconductor lithography, is to be obtained, it has been difficult to obtain a sufficiently wide spectral linewidth by the optical phase modulation alone.

6 FIG. 6 FIG. 1 FIG. 1 FIG. 11 11 21 20 schematically illustrates a configuration of a laser apparatusaccording to Embodiment 1. The configuration illustrated inwill be described in terms of differences from the configuration illustrated in. The laser apparatusincludes a solid-state seederinstead of the solid-state seederin.

7 FIG. 7 FIG. 2 FIG. 21 21 200 210 100 110 schematically illustrates a configuration of the solid-state seeder. The configuration illustrated inwill be described in terms of differences from the configuration illustrated in. The solid-state seederincludes a first solid-state laser deviceand a second solid-state laser deviceinstead of the first solid-state laser deviceand the second solid-state laser device.

200 101 202 203 204 The first solid-state laser deviceincludes the semiconductor laser system, a solid-state amplifier, a solid-state amplifier, and a solid-state amplifier.

202 203 The solid-state amplifierand the solid-state amplifiermay each be a semiconductor optical amplifier (SOA). The SOA is, for example, a multiple quantum well structure of InP/InGaAsP.

202 101 1 160 202 The solid-state amplifiercuts out a portion of the CW laser beam output from the semiconductor laser systemin a pulse shape and amplifies it to attain a first pulse laser beam PLby a trigger 3 signal sent from the solid-state seeder control processor. The solid-state amplifieris an example of a “first amplifier”in the present disclosure.

203 1 2 160 203 The solid-state amplifierfurther cuts out and amplifies a portion of the first pulse laser beam PLto attain a second pulse laser beam PLby a trigger 1 signal sent from the solid-state seeder control processor. The trigger 1 signal is an example of a “first trigger signal” in the present disclosure. The solid-state amplifieris an example of a “second amplifier” in the present disclosure.

204 204 2 160 5 204 204 The solid-state amplifieris, for example, an optical fiber amplifier doped with Yb of rare earth ions. The solid-state amplifieramplifies power of the second pulse laser beam PLbased on a gain signal sent from the solid-state seeder control processorto attain a fifth pulse laser beam PL. In the following, an amplification gain of the solid-state amplifieris referred to as Gain. The solid-state amplifieris an example of a “fourth amplifier” in the present disclosure.

210 116 110 113 111 3 160 113 The second solid-state laser devicedoes not include the dichroic mirroras compared to the second solid-state laser device. The solid-state amplifiercuts out the CW laser beam output from the semiconductor laser systemin the pulse shape and amplifies it to attain a third pulse laser beam PLby a trigger 2 signal sent from the solid-state seeder control processor. The trigger 2 signal is an example of a “second trigger signal” in the present disclosure. The solid-state amplifieris an example of a “third amplifier”in the present disclosure.

114 3 113 115 114 6 The LBO crystalconverts the third pulse laser beam PLhaving the wavelength of about 1030 nm from the solid-state amplifier, which is modulated and cut out in the pulse shape, to the pulse laser beam having the wavelength of about 515 nm. The CLBO crystalconverts the pulse laser beam having the wavelength of about 515 nm converted by the LBO crystalto a sixth pulse laser beam PLhaving the wavelength of about 257.6 nm.

5 200 6 210 141 140 4 142 21 The fifth pulse laser beam PLhaving the wavelength of about 1554 nm output from the first solid-state laser deviceand the sixth pulse laser beam PLhaving the wavelength of about 257.6 nm output from the second solid-state laser deviceare subjected to sum-frequency mixing by the CLBO crystalof the wavelength conversion system, and are wavelength-converted to the pulse laser beam having the wavelength of about 220.9 nm. Further, the pulse laser beam having the wavelength of about 220.9 nm is converted to a fourth pulse laser beam PLhaving the wavelength of about 193.4 nm by the CLBO crystal, and is output from the solid-state seeder.

140 2 203 200 5 The wavelength conversion systemmay perform sum-frequency mixing using the second pulse laser beam PL, which is output of the solid-state amplifierof the first solid-state laser device, instead of the fifth pulse laser beam PL.

140 200 210 21 200 210 Further, the wavelength conversion systemmay be formed of an optical crystal that performs sum-frequency mixing at a wavelength different from the above example, the pulse laser beam from the first solid-state laser deviceand the pulse laser beam from the second solid-state laser devicemay be subjected to sum-frequency mixing and wavelength-converted to be output of the solid-state seeder. In this case, the pulse laser beam from the first solid-state laser deviceand the pulse laser beam from the second solid-state laser devicemay be the ones outputting the wavelength different from the above example, respectively.

140 2 5 200 3 6 210 That is, the wavelength conversion systemmay perform sum-frequency mixing, for wavelength-conversion, of the second pulse laser beam PLor the fifth pulse laser beam PLfrom the first solid-state laser deviceand the third pulse laser beam PLor the sixth pulse laser beam PLfrom the second solid-state laser device.

50 61 60 160 6 FIG. The laser control processorgenerates the trigger A signal and the trigger B signal in synchronization with the light emission trigger signal sent from the exposure control processorof the exposure apparatusillustrated in. The solid-state seeder control processorgenerates the trigger 1 signal, the trigger 2 signal, and the trigger 3 signal in synchronization with the trigger B signal. Therefore, the trigger 1 signal, the trigger 2 signal, and the trigger 3 signal are synchronized with the light emission trigger signal.

8 FIG. 1 21 illustrates a timing chart at the time of laser operation execution when timing adjustment to be described later in Embodimentis completed and the solid-state seederis operated.

160 101 111 50 160 101 111 (1) The solid-state seeder control processorcontrols the oscillation wavelength and the output of CW light of the semiconductor laser systemand the semiconductor laser systembased on the received temperature value and current value. 160 150 151 150 (2) The solid-state seeder control processoroperates the pseudorandom signal generatorafter resetting the shift registerof the pseudorandom signal generatorbased on the timing of the trigger B signal. 160 1 1 200 202 101 1 1 1 (3) The solid-state seeder control processorgenerates the trigger 3 signal having a pulse width Wby adding Delaywhich is delay time based on the timing of the trigger B signal as control of the first solid-state laser device. The solid-state amplifieramplifies the CW light having the wavelength of about 1554 nm output from the semiconductor laser system, and converts it to the first pulse laser beam PL. The pulse width of the first pulse laser beam PLis about W. 160 2 2 203 1 202 2 2 160 1 2 (4) The solid-state seeder control processorgenerates the trigger 1 signal having a pulse width Wby adding Delaywhich is the delay time further to the timing of the trigger 3 signal. The solid-state amplifierfurther amplifies the first pulse laser beam PLoutput from the solid-state amplifierand cuts it out by a time width in which the pulse width is about Wto generate the second pulse laser beam PL. The solid-state seeder control processormay add the delay time of Delay+Delaybased on the trigger B signal to generate the trigger 1 signal. 2 203 204 5 160 204 5 200 (5) The second pulse laser beam PLoutput by the solid-state amplifieris further amplified in power by the solid-state amplifierto be the fifth pulse laser beam PL. The solid-state seeder control processorcontrols Gain of the solid-state amplifierto adjust the power of the fifth pulse laser beam PL, which is the output of the first solid-state laser device. 160 3 3 210 113 111 112 3 3 3 (6) Meanwhile, the solid-state seeder control processorgenerates the trigger 2 signal having a pulse width Wby adding Delaywhich is the delay time based on the timing of the trigger B signal as the control of the second solid-state laser device. The solid-state amplifieramplifies the CW light having the wavelength of about 1030 nm output from the semiconductor laser systemand modulated by the optical phase modulatorand cuts it out in the pulse shape to attain the third pulse laser beam PL. The pulse width of the third pulse laser beam PLis about W. The solid-state seeder control processorreceives the spectral linewidth control signal, the temperature value and the current value for the semiconductor laser systemand the semiconductor laser system, and the trigger B signal from the laser control processor, and executes following control operations (1) to (6).

3 114 115 6 210 The third pulse laser beam PLis wavelength-converted to the pulse laser beam having the wavelength of about 257.6 nm via the LBO crystaland the CLBO crystalto be the sixth pulse laser beam PLas output light of the second solid-state laser device.

160 143 144 140 5 200 6 210 4 141 142 Thereafter, the solid-state seeder control processoradjusts the rotation stageand the rotation stageof the wavelength conversion systemand converts the fifth pulse laser beam PLwhich is the output of the first solid-state laser deviceand the sixth pulse laser beam PLwhich is the output of the second solid-state laser deviceto the fourth pulse laser beam PLhaving the wavelength of about 193.4 nm through two-stage sum-frequency mixing (the CLBO crystaland the CLBO crystal).

4 21 5 6 As described above, the fourth pulse laser beam PLwhich is the output of the solid-state seederis generated by overlap of the timings of the fifth pulse laser beam PLand the sixth pulse laser beam PL.

4 Therefore, the fourth pulse laser beam PLis generated based on the overlap of the trigger 1 signal and the trigger 2 signal.

10 50 61 60 30 21 11 In the operation at the time of the laser operation execution, similarly to the laser apparatus, the laser control processorreceives the target center wavelength, the target linewidth, the target pulse energy, and the light emission trigger signal from the exposure control processorof the exposure apparatus, sends the trigger A signal and the charging voltage value to the excimer amplifierand sends the trigger B signal, the linewidth control signal, the temperature value, and the current value to the solid-state seederto operate the laser apparatus, and controls the pulse laser beam.

112 112 112 With the configuration and the operation, since the pseudorandom signal of the same pattern is generated in synchronization with the trigger 2 signal synchronized with the timing of the light emission trigger signal and is superimposed onto the optical phase modulator, the modulation signal of the same waveform for each pulse is superimposed onto the optical phase modulator, and the spectrum of the signal to be superimposed is also the same for each pulse. Therefore, since the laser beam output from the optical phase modulatoris modulated the same for each pulse, the spectrum becomes the same for each pulse, the spectral linewidth also becomes the same for each pulse and becomes stable.

11 10 Further, with the configuration and the operation, the laser apparatuscan output the laser beam of a wide unimodal spectrum with an enlarged adjustment range of the spectral linewidth as compared to the laser apparatus.

21 A spectral linewidth timing adjusting method for outputting the wide unimodal spectrum from the solid-state seederwill be described.

9 FIG. 9 FIG. illustrates a flowchart at the time of the timing adjustment. As illustrated in, the timing adjustment includes a first step and a second step executed following the first step.

4 4 4 In the first step, at least one of the timing of the trigger 1 signal and the timing of the trigger 2 signal is adjusted, and the spectrum of the fourth pulse laser beam PLis adjusted to a first spectrum in a non-Gaussian shape. Here, in the first step, by changing a start timing of the trigger 1 signal and measuring the spectrum of the fourth pulse laser beam PL, the start timing of the trigger 1 signal at which the spectrum of the fourth pulse laser beam PLbecomes the first spectrum in the non-Gaussian shape is searched.

10 FIG. 21 160 150 160 2 illustrates a flowchart of the first step. In step S, the solid-state seeder control processorstops the pseudorandom signal generator. In addition, the solid-state seeder control processorsets Delayto 0.

22 160 2 1 2 1 2 22 2 1 2 160 23 In step S, the solid-state seeder control processordetermines whether Delayis smaller than (W−W). Wis the width of the trigger 3 signal, and Wis the width of the trigger 1 signal. If a determination result in step Sis NO determination, that is, if Delayis not smaller than (W−W), the solid-state seeder control processorproceeds to step S.

23 160 In step S, the solid-state seeder control processordetermines that it is an error (non-adjustable) and ends processing of the timing adjustment.

22 2 1 2 160 24 On the other hand, if the determination result in step Sis YES determination, that is, if Delayis smaller than (W−W), the solid-state seeder control processorproceeds to step S.

24 160 4 4 43 43 4 30 21 30 4 In step S, the solid-state seeder control processormeasures the spectrum of the fourth pulse laser beam PL. The spectrum of the fourth pulse laser beam PLmay be measured by the spectrum monitor. In this case, the spectrum monitormeasures the spectrum of the light obtained by amplifying the fourth pulse laser beam PLby the excimer amplifier. Alternatively, a beam splitter may be installed between the solid-state seederand the excimer amplifierto monitor the spectrum of the fourth pulse laser beam PL.

25 160 4 In step S, the solid-state seeder control processordetermines whether the spectrum of the fourth pulse laser beam PLis a non-Gaussian waveform which is a waveform in the non-Gaussian shape.

25 160 26 26 160 2 22 If a determination result in step Sis NO determination, that is, if the spectrum is not the non-Gaussian waveform, the solid-state seeder control processorproceeds to step S. In step S, the solid-state seeder control processoradds a fixed value to Delayand returns to step S.

25 160 27 27 160 4 On the other hand, if the determination result in step Sis YES determination, that is, if the spectrum is the non-Gaussian waveform, the solid-state seeder control processorproceeds to step S. In step S, the solid-state seeder control processordetermines whether a difference between the spectral linewidth of the fourth pulse laser beam PLand the predetermined target linewidth at the time of adjustment is within an allowable range.

27 160 26 If a determination result in step Sis NO determination, that is, if the difference from the target linewidth at the time of the adjustment is not within the allowable range, the solid-state seeder control processorproceeds to step S.

27 160 2 2 4 2 On the other hand, if the determination result in step Sis YES determination, that is, if the difference from the target linewidth at the time of the adjustment is within the allowable range, the solid-state seeder control processorends the processing of the present flowchart and determines a value of Delay. The most appropriate Delaymay be selected by measuring the spectrum of the fourth pulse laser beam PLfor all Delay.

11 FIG. 10 FIG. 11 FIG. 160 150 2 210 4 illustrates a timing chart in the first step. As illustrated inand, in the first step, the solid-state seeder control processorstops the pseudorandom signal generatorand changes Delayin a state of not applying optical phase modulation of the second solid-state laser deviceto adjust the fourth pulse laser beam PLto the first spectrum having the wider spectral linewidth than a Gaussian shape.

12 FIG. 12 FIG. 12 FIG. 4 2 2 4 illustrates the spectrum of the fourth pulse laser beam PLin the adjustment in the first step. For waveforms A, B, and C illustrated in, Delayis 9 nsec, 11 nsec, and 13 nsec respectively, Gain is 0.8 V respectively, and the E95 width is 0.08 pm, 0.16 pm, and 0.23 pm respectively. When Delayis changed, as illustrated in, the spectrum of the fourth pulse laser beam PLchanges from a narrow Gaussian shape (unimodal) to the spectrum having the spectral linewidth wider than the Gaussian shape, and further changes to a multimodal spectrum.

2 2 12 FIG. 12 FIG. In the first step, Delayto be a wide spectrum such as the waveforms B and C illustrated inis selected. In the first step, when Delayto be a narrow unimodal spectrum such as the waveform A illustrated inis selected, it is difficult to obtain a wide spectrum when phase modulation by the pseudorandom signal is applied in the second step.

4 25 2 2 10 FIG. Note that whether the fourth pulse laser beam PLin step Sinis the non-Gaussian waveform is determined by fitting the measured spectrum with the Gaussian waveform by a least squares method and using a size of a determination coefficient R. For example, if Ris smaller than 0.9, it is determined to be the non-Gaussian waveform.

13 13 FIGS.A andB 13 13 FIGS.A andB 13 FIG.A 13 FIG.A 2 2 illustrate determination examples of the non-Gaussian waveform.each include graphs indicating the measured spectra and Gaussian fitting waveforms. The spectrum insatisfies R=0.9876 and does not satisfy R<0.9. Therefore, the spectrum inis determined to be the Gaussian waveform.

13 FIG.B 13 FIG.B 2 2 On the other hand, the spectrum insatisfies R=0.7411 and satisfies R<0.9. Therefore, the spectrum inis determined to be the non-Gaussian waveform.

2 1 2 2 1 2 5 200 2 2 5 4 21 In the first step, the spectrum is adjusted by changing Delaywithin a range of 0 to (W−W). When Delayis negative or is larger than (W−W), a time width of the fifth pulse laser beam PLwhich is the output of the first solid-state laser deviceis shorter than W. Further, when Delayis shifted such that there is no temporal overlap of the trigger 3 signal and the trigger 1 signal, the fifth pulse laser beam PLand even the fourth pulse laser beam PLwhich is the output of the solid-state seederare eliminated so that attention needs to be paid.

3 3 Similarly, attention needs to be paid to setting Delayand Wso as to generate the overlap of the trigger 1 signal and the trigger 2 signal.

4 21 By adjusting the timing based on the above, the fourth pulse laser beam PLis output from the solid-state seederaccording to the timing of the trigger 1 signal.

1 2 30 2 21 30 1 3 1 A length of Delay+Delaythat determines the timing of the trigger 1 signal needs to be adjusted in accordance with an optical amplification timing of the excimer amplifier. Therefore, in the first step, after adjusting Delay, the adjustment may be executed such that the output pulse laser beam of the solid-state seederoverlaps with the amplification timing of the excimer amplifierby changing the timing of the trigger 1 signal by Delay. At that time, Delaymay be also changed in accordance with change of Delayso that a relative timing difference between the trigger 3 signal and the trigger 2 signal does not change.

1 3 2 Alternatively, in the first step, Delayand Delaymay be fixed, and after adjusting Delay, the adjustment may be executed so that a time difference between the trigger A signal and the trigger B signal becomes an appropriate amplification timing.

150 112 3 4 150 4 151 150 4 In the second step, by causing the pseudorandom signal generatorto generate the modulation signal of the same pattern synchronized with the light emission trigger signal and supplying the modulation signal of the same pattern to the optical phase modulator, the wavelength of the second continuous light is modulated within the time corresponding to one pulse of the third pulse laser beam PLand the spectrum of the fourth pulse laser beam PLis adjusted to a second spectrum having the spectral linewidth wider than the first spectrum. Here, in the second step, the pseudorandom signal generatoris operated, the spectrum of the fourth pulse laser beam PLis observed, and a search is performed by changing the initial value of the shift registerof the pseudorandom signal generatorso that the spectrum of the fourth pulse laser beam PLbecomes the second spectrum which is unimodal and wide.

14 FIG. 31 160 150 illustrates a flowchart of the second step. In step S, the solid-state seeder control processoroperates the pseudorandom signal generator.

32 160 4 In step S, the solid-state seeder control processormeasures the spectrum of the fourth pulse laser beam PL.

33 160 4 In step S, the solid-state seeder control processordetermines whether the spectrum of the fourth pulse laser beam PLis unimodal.

33 160 34 34 160 151 32 If a determination result in step Sis NO determination, that is, if the spectrum is not unimodal, the solid-state seeder control processorproceeds to step S. In step S, the solid-state seeder control processorupdates the initial value of the shift registerand returns to step S.

33 160 35 35 160 4 On the other hand, if the determination result in step Sis YES determination, that is, if the spectrum is unimodal, the solid-state seeder control processorproceeds to step S. In step S, the solid-state seeder control processordetermines whether a difference between the spectral linewidth of the fourth pulse laser beam PLand the unimodal target linewidth is within an allowable range.

35 160 34 If a determination result in step Sis NO determination, that is, if the difference from the unimodal target linewidth is not within the allowable range, the solid-state seeder control processorproceeds to step S.

35 160 151 151 On the other hand, if the determination result in step Sis YES determination, that is, if the difference from the unimodal target linewidth is within the allowable range, the solid-state seeder control processorends the processing of the present flowchart and determines the initial value of the shift register. The most appropriate initial value may be selected by executing evaluation of the spectrum for all the initial values of the shift register.

15 FIG. 15 FIG. 12 FIG. 15 FIG. 12 FIG. 15 FIG. 4 4 151 2 illustrates the spectrum of the fourth pulse laser beam PLafter the search in the second step. Waveforms A, B, and C inare the spectrums of the fourth pulse laser beam PLafter the initial value of the shift registeris determined for the waveforms A, B, and C in, respectively. For the waveforms A, B, and C illustrated in, the E95 width is 0.24 pm, 0.32 pm, and 0.4 pm respectively. When a wide multimodal spectrum such as the waveform C inis selected in the adjustment of Delay, a wide unimodal spectrum such as the waveform C inis obtained.

12 FIG. 15 FIG. In contrast, when a narrow unimodal spectrum such as the waveform A inis selected, a narrow unimodal spectrum such as the waveform A inis obtained.

10 20 150 110 20 150 151 150 102 10 102 102 2 12 FIG. 15 FIG. 12 FIG. In the laser apparatusaccording to the comparative example, the output pulse laser beam of the solid-state seederin a state where the pseudorandom signal generatoris stopped and the optical phase modulation of the second solid-state laser deviceis not applied corresponds to the waveform A in. It is because that, since a goal is to eventually make the output pulse laser beam of the solid-state seederunimodal (Gaussian shape), if the spectrum is made unimodal (Gaussian shape) even in the state where the phase modulation is not applied, it becomes easy to operate the pseudorandom signal generatorthereafter and to perform a search by changing the initial value of the shift registerof the pseudorandom signal generatorso that the spectrum has a unimodal shape (the waveform A in). Therefore, the spectrum of the pulse laser beam output from the solid-state amplifierof the laser apparatusaccording to the comparative example is designed and manufactured so as to be the Gaussian shape (the waveform A in). Further, since the solid-state amplifieruses the pulse laser beam having the wavelength of 1030 nm that cannot be wavelength-converted in the LBO crystal as the pump light, the adjustment of the amplification timing of the solid-state amplifierwhich corresponds to the adjustment of Delayin Embodiment 1 is difficult.

11 2 150 210 11 151 150 12 FIG. 15 FIG. 12 FIG. 15 FIG. On the other hand, the laser apparatusaccording to Embodiment 1 adjusts Delayin the state where the pseudorandom signal generatoris stopped and the optical phase modulation of the second solid-state laser deviceis not applied, as the first step. Thus, the spectrum having the spectral linewidth that is not the Gaussian shape and is wider than the Gaussian shape, such as the waveform B or the waveform C in, is once attained. Thereafter, as the second step, the laser apparatusperforms a search by changing the initial value of the shift registerof the pseudorandom signal generatorin the state where the optical phase modulation is applied. Thus, it is possible to shape the spectrum to obtain the wide and unimodal spectrum such as the waveform B or the waveform C in. In particular, by once performing the adjustment to the multimodal spectrum such as the waveform C in, it is possible to eventually obtain the wider spectrum such as the waveform C in.

11 11 160 A configuration of the laser apparatus according to Embodiment 2 is the same as the configuration of the laser apparatus according to Embodiment 1. The laser apparatusaccording to Embodiment 2 differs from the laser apparatusaccording to Embodiment 1 in contents of the control executed by the solid-state seeder control processor.

204 4 2 In the first step of Embodiment 2, at least one of the timing of the trigger 1 signal and the timing of the trigger 2 signal is adjusted, Gain of the solid-state amplifieris also adjusted, and the spectrum of the fourth pulse laser beam PLis adjusted to the first spectrum in the non-Gaussian shape. Here, in addition to the adjustment of Delay, Gain is further adjusted to obtain the wide unimodal spectrum. The second step of Embodiment 2 is the same as that of Embodiment 1.

16 FIG. 41 160 150 160 2 illustrates a flowchart of the first step of Embodiment 2. In step S, the solid-state seeder control processorstops the pseudorandom signal generator. In addition, the solid-state seeder control processorsets Delayto 0 and Gain to a minimum value.

22 25 27 25 27 160 2 10 FIG. The processing of steps Sto Sand step Sis the same as that in. If the determination result in step Sis YES determination and the determination result in step Sis also YES determination, the solid-state seeder control processorends the processing of the present flowchart and determines values of Delayand Gain.

25 27 160 42 42 160 On the other hand, if the determination result in step Sis NO determination or the determination result in step Sis NO determination, the solid-state seeder control processorproceeds to step S. In step S, the solid-state seeder control processordetermines whether Gain is smaller than a maximum value.

42 160 43 43 160 26 160 2 22 If a determination result in step Sis NO determination, that is, if Gain is not smaller than the maximum value, the solid-state seeder control processorproceeds to step S. In step S, the solid-state seeder control processorsets Gain to the minimum value. Thereafter, in step S, the solid-state seeder control processoradds a fixed value to Delayand returns to step S.

42 160 44 44 160 4 On the other hand, if the determination result in step Sis YES determination, that is, if Gain is smaller than the maximum value, the solid-state seeder control processorproceeds to step S. In step S, the solid-state seeder control processormeasures the spectrum of the fourth pulse laser beam PL.

45 160 4 25 In step S, the solid-state seeder control processordetermines whether the spectrum of the fourth pulse laser beam PLis the non-Gaussian waveform. This determination may be made similarly to step S.

45 160 46 46 160 42 If a determination result in step Sis NO determination, that is, if the spectrum is not the non-Gaussian waveform, the solid-state seeder control processorproceeds to step S. In step S, the solid-state seeder control processorincrements Gain by a fixed amount and returns to step S.

45 160 47 47 160 4 On the other hand, if the determination result in step Sis YES determination, that is, if the spectrum is the non-Gaussian waveform, the solid-state seeder control processorproceeds to step S. In step S, the solid-state seeder control processordetermines whether the difference between the spectral linewidth of the fourth pulse laser beam PLand the target linewidth at the time of the adjustment is within an allowable range.

47 160 46 47 160 2 If a determination result in step Sis NO determination, that is, if the difference from the target linewidth at the time of the adjustment is not within the allowable range, the solid-state seeder control processorproceeds to step S. On the other hand, if the determination result in step Sis YES determination, that is, if the difference from the target linewidth at the time of the adjustment is within the allowable range, the solid-state seeder control processorends the processing of the present flowchart and determines the values of Delayand Gain.

2 2 2 In the first step of Embodiment 2, if a desired multimodal spectrum is obtained only by adjusting Delay, the adjustment of Gain may not be executed as in Embodiment 1. On the other hand, if the desired multimodal spectrum cannot be obtained only by adjusting Delay, Gain is adjusted. It is also possible to adjust Gain first and adjust Delaywhen the desired multimodal spectral cannot be obtained.

2 The spectrums in all combinations of Delayand Gain may be examined to select the best one.

17 FIG. 17 FIG. 4 2 illustrates the spectrum of the fourth pulse laser beam PLin the adjustment in the first step. For waveforms A, B, and C illustrated in, Delayis 9 nsec, 11 nsec, and 13 nsec respectively, Gain is 0.8 V, 1.1 V, and 1.4V respectively, and the E95 width is 0.08 pm, 0.19 pm, and 0.3 pm respectively.

18 FIG. 18 FIG. 17 FIG. 18 FIG. 4 4 151 illustrates the spectrum of the fourth pulse laser beam PLafter the search in the second step. Waveforms A, B, and C inare the spectrums of the fourth pulse laser beam PLafter the initial value of the shift registeris determined for the waveforms A, B, and C in, respectively. For the waveforms A, B, and C illustrated in, the E95 width is 0.24 pm, 0.37 pm, and 0.5 pm, respectively.

17 FIG. 18 FIG. 2 As illustrated inand, a wider spectrum is obtained by combining the adjustment of Delayand the adjustment of Gain.

11 11 160 A configuration of the laser apparatus according to Embodiment 3 is the same as the configuration of the laser apparatus according to Embodiment 1. The laser apparatusaccording to Embodiment 3 differs from the laser apparatusaccording to Embodiment 1 in contents of the control executed by the solid-state seeder control processor.

3 4 4 In the first step of Embodiment 3, by changing Delaywhich is a start timing of the trigger 2 signal and measuring the spectrum of the fourth pulse laser beam PL, the start timing of the trigger 2 signal at which the spectrum of the fourth pulse laser beam PLbecomes the first spectrum in the non-Gaussian shape is searched. The second step of Embodiment 3 is the same as that of Embodiment 1.

19 FIG. 61 160 150 160 3 1 2 2 3 illustrates a flowchart of the first step of Embodiment 3. In step S, the solid-state seeder control processorstops the pseudorandom signal generator. In addition, the solid-state seeder control processorsets Delayto (Delay+Delay+W−W).

62 160 3 1 2 62 3 1 2 160 23 23 23 10 FIG. In step S, the solid-state seeder control processordetermines whether Delayis smaller than (Delay+Delay). If a determination result in step Sis NO determination, that is, if Delayis not smaller than (Delay+Delay), the solid-state seeder control processorproceeds to step S. The processing of step Sis the same as that of step Sin.

62 3 1 2 160 24 On the other hand, if the determination result in step Sis YES determination, that is, if Delayis smaller than (Delay+Delay), the solid-state seeder control processorproceeds to step S.

24 25 27 24 25 27 25 27 160 3 10 FIG. The processing of steps S, S, and Sis the same as that of steps S, S, and Sin. If the determination result in step Sis YES determination and the determination result in step Sis also YES determination, the solid-state seeder control processorends the processing of the present flowchart and determines a value of Delay.

25 27 160 63 63 160 3 62 On the other hand, if the determination result in step Sis NO determination or the determination result in step Sis NO determination, the solid-state seeder control processorproceeds to step S. In step S, the solid-state seeder control processoradds a fixed value to Delayand returns to step S.

200 210 3 4 3 4 3 Thus, a difference in a pulse cut-out timing between the first solid-state laser deviceand the second solid-state laser deviceis adjusted by adjusting Delay, and the spectrum of the fourth pulse laser beam PLis adjusted to be wide and multimodal. The most appropriate Delaymay be selected by measuring the spectrum of the fourth pulse laser beam PLfor all Delay.

3 3 3 3 3 1 2 2 3 3 1 2 Delay+Delay+W−W<Delay<Delay+Delay. . . (Expression 1) When Delayis to be adjusted, attention needs to be paid to setting Delayand Wso as to generate the overlap of the trigger 1 signal and the trigger 2 signal. Specifically, Delayand Ware set so as to satisfy Expression 1 below.

3 1 1 Further, the adjustment of Delayin the first step of Embodiment 3 may be executed in combination with the adjustment of Delayof Embodiment 1, may be executed in combination with the adjustment of Gain of Embodiment 2, or may be executed in combination with the adjustment of Delayand Gain of Embodiment 2.

20 FIG. 20 FIG. 4 2 3 illustrates the spectrum of the fourth pulse laser beam PLin the adjustment in the first step. For waveforms A, B, and C illustrated in, Delayis 9 nsec respectively, Delayis 9962 ns, 9963 ns, and 9964 ns respectively, Gain is 0.8 V respectively, and the E95 width is 0.08 pm, 0.20 pm, and 0.33 pm respectively.

21 FIG. 4 illustrates the spectrum of the fourth pulse laser beam PLafter the search in the second step.

21 FIG. 20 FIG. 21 FIG. 4 151 Waveforms A, B, and C inare the spectrums of the fourth pulse laser beam PLafter the initial value of the shift registeris determined for the waveforms A, B, and C in, respectively. For the waveforms A, B, and C illustrated in, the E95 width is 0.24 pm, 0.40 pm, and 0.55 pm, respectively.

20 FIG. 21 FIG. 3 As illustrated inand, a wider spectrum is obtained by adjusting Delay.

50 61 The processor such as the laser control processorand the exposure control processormay be physically configured as hardware to execute the various kinds of processing included in the present disclosure. For example, the processor may be a computer including a memory that stores a control program defining the various kinds of processing and a processing device that executes the control program. The control program may be stored in one memory, or may be stored separately in a plurality of memories at physically separate locations, and the various kinds of processing may be defined by a combination of control programs stored in the memories. The processing device may be a general-purpose processing device such as a CPU or a special-purpose processing device such as a GPU.

Alternatively, the processor may be programmed as software to execute the various kinds of processing included in the present disclosure. For example, for the processor, functions to execute the various kinds of processing may be implemented in a dedicated device such as an ASIC or a programmable device such as a FPGA.

The various kinds of processing included in the present disclosure may be executed by one computer, one dedicated device, or one programmable device, or may be executed by cooperation of a plurality of computers, a plurality of dedicated devices, or a plurality of programmable devices at physically separate locations. The various kinds of processing may be executed by a combination including at least any two of: one or more computers, one or more dedicated devices, and one or more programmable devices.

22 FIG. 60 60 62 63 11 60 62 11 63 schematically illustrates a configuration example of the exposure apparatus. The exposure apparatusincludes an illumination optical systemand a projection optical system. The laser apparatusgenerates a laser beam, and outputs the laser beam to the exposure apparatus. The illumination optical systemilluminates a reticle pattern of an unillustrated reticle disposed on a reticle stage RT with the laser beam incoming from the laser apparatus. The projection optical systemperforms reduced projection of the laser beam transmitted through the reticle, and forms an image on an unillustrated workpiece disposed on a workpiece table WT. The workpiece is a photosensitive substrate such as a semiconductor wafer on which photoresist is applied.

60 The exposure apparatussynchronously translates the reticle stage RT and the workpiece table WT to expose the workpiece to the laser beam reflecting the reticle pattern. After the reticle pattern is transferred onto the semiconductor wafer by an exposure process as above, a semiconductor device can be manufactured through a plurality of processes. The semiconductor device is an example of an “electronic device” in the present disclosure.

The description above is intended to be illustrative and the present disclosure is not limited thereto. Therefore, it would be obvious to those skilled in the art that various modifications to the embodiments of the present disclosure would be possible without departing from the spirit and the scope of the appended claims. Further, it would be also obvious to those skilled in the art that embodiments of the present disclosure would be appropriately combined.

The terms used throughout the present specification and the appended claims should be interpreted as non-limiting terms unless clearly described. For example, terms such as “comprise”, “include”, “have”, and “contain” should not be interpreted to be exclusive of other structural elements. Further, indefinite articles “a/an” described in the present specification and the appended claims should be interpreted to mean “at least one” or “one or more.” Further, “at least one of A, B, and C” should be interpreted to mean any of A, B, C, A+B, A+C, B+C, and A+B+C as well as to include combinations of any thereof and any other than A, B, and C.